I said this elsewhere on here but I'll reiterate, this is not something exclusive to this franchise or subreddit, it's a problem with how fans of long running franchises act whenever there's a new entry in said franchise that they personally don't like or is honestly a divisive entry, or just flat out bad. Particularly online fans I haven't really run into it irl.
If someone likes that entry, and they voice that opinion online, the people who don't like that entry typically take a nasty or condescending tone and try to invalidate not only the persons opinion but also them as fan, by calling them a "fake fan" a "shill" or asking "what's it like being on 'whatever movie studio' made this movie's payroll?" or whatever dumbass variation of that shit they come up with. They can say why they like it in the most noncombative way and still get downvoted and nasty comments. Doesn't matter if that fan has been a fan since they were in elementary school, they either don't believe them cause they can't fathom someone liking a movie they don't while still being a fan, or they don't care and just enjoy being an asshole.
It happened with Star Wars with the sequel trilogy and also the prequel trilogy before it became cool to like those and the prequel kids grew up and entered online fandom spaces. And it's happened with countless other franchises, the MCU is starting to get old enough that we're beginning to see that elitism pop up in that fandom.